Combined preparations with barbiturates are mainly classified in A03 (mainly antispasmodic effect) or in N02 (mainly analgesic effect).Combined preparations with barbiturates which remain in N05C are mainly "neurostabilizers".

The group is subdivided according to chemical structure.

The DDDs are based on use of the drugs as hypnotics.

The DDD for melatonin is based on dose recommendations in EU for the 2 mg depot tablet.